Enabling NDMP breaks CIFS backups

I've been using Backup Exec to backup data from CIFS shares from our FAS2040 for a few years with no problems.

I enabled NDMP on the filer the other day to allow me to monitor snapmirror relationships with the Disaster Recovery module in DFM. Since doing that, Backup Exec cannot connect to the CIFS shares to perform backups.

Browsing CIFS shares is fine, only the backup jobs fail. If I disable NDMP on the filer, the backups work again. We do not have the NDMP option in Backup Exec and I don't want it. The tape drive is connected directly to the backup server and is used for other jobs as well and I just want to continue to backup the FAS across the network from the shares.

With NDMP enabled:

If I use the ndmp user I setup for DFM for the backup job, I get the error "A network connection could not be established" in Backup Exec.

If I use the domain account, I get an "Access Denied" error in Backup Exec.

DFM Snapmirror monitoring is OK.

With NDMP disabled:

If I use the ndmp user I setup for DFM for the backup job, I get an "Access Denied" error in Backup Exec.

If I use the usual domain account, backups work fine.

DFM Snapmirror monitoring does not work for obvious reasons.

It seems that Backup Exec is trying to use NDMP even when it shouldn't be. I can't see any options in Backup Exec to stop thjis from happening and have spent all morning searching through the (quite frustrating) Symantec support site with no luck.

I realise this is more a Backup Exec problem but is there anything anyone can think of that may help me get round this? At the moment my choices are either have NDMP enabled and monitor snapmirror in DFM or have NDMP disabled and have tape backup.

I have tried enabling NDMP but restricting access to only the DFM server but that didn't help.